Display device and display optical system unit

ABSTRACT

A display apparatus having a reflecting type light valve which has a light incidence/reflection surface, a drive circuit which drives the reflecting type light valve by supplying an image signal, a cooling system which cools at least the reflecting type light valve with cooling fluid, and a partition wall which partitions a space in the display apparatus into a cooling fluid side and a light incidence/reflection side. The reflecting type light valve forms a part of the partition wall, and the light incidence/reflection surface faces the light incidence/reflection side and a part opposite to the light incidence/reflection surface of the reflecting type light valve is cooled by the cooling system.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This is a continuation of U.S. application Ser. No. 09/446,336,filed Dec. 20, 1999, the subject matter of which is incorporated byreference herein.

TECHNICAL FIELD

[0002] The present invention relates to a display device, such as aliquid crystal projector device, a liquid crystal television set, and aprojection type display device or the like, which projects a video imageon a screen by utilizing a light valve device, such as a liquid crystalpanel.

BACKGROUND OF THE INVENTION

[0003] There is a projection type display device, such as a liquidcrystal projector, which changes light from a light source, such as anelectric bulb, to a contrast per pixel image using a light valve device,such as a liquid crystal panel, and projects an enlarged image on ascreen or the like. Further, as the light valve device of the displaydevice, devices of two operation types, a light transmitting type lightvalve device and a reflecting type light valve device, are known.

[0004] The light valve device generally comprises a semiconductordriving device and an optical function material such as liquid crystalor the like. To normally operate both constituents, a predeterminedtemperature (e.g., 60° C.) or lower must be maintained in the device. Onthe other hand, light from the light source, except for light that is tobe finally projected, is absorbed by the light valve device and itsperipheral optical elements and the like, and this light turns to heat.Accordingly, in a projection type video display device, the light valvedevice must be cooled so as not to overheat beyond a range of normaloperation. The significance of cooling is becoming more and moreimportant with an increase in the intensity of the light-source lightfor recent high-brightness projection video images, since the increasein the light-source light intensity increases the amount of heatgeneration which occurs in the light valve device.

[0005] Further, in such a display device, as the optical system bringsthe light of the image from the light valve device into focus, images offoreign particles, such as dust attached around the light valve device,are enlarged and projected on the screen or the like. Accordingly,prevention of dust around the light valve device is also an importantproblem to be solved.

[0006] Conventionally, a display device using a reflecting type lightvalve device is disclosed in Japanese Published Unexamined PatentApplication No. Sho 64-5174. Further, a technique to cool the reflectingtype light valve device in a display device is disclosed in JapanesePublished Unexamined Patent Application No. Sho 62-294230. According tothis technique, a cooling device is provided on the rear of a liquidcrystal panel operating as the reflecting type light valve device.

[0007] Further, a technique to prevent dust in the display device isdisclosed in Japanese Published Unexamined Patent Application, No. Hei7-152009. According to this technique, a liquid crystal panel operatingas a light transmitting type light valve device is placed within anenclosed space, and air within the enclosed space is circulated toradiate heat generated by the liquid crystal panel and transmit the heatto the outside of the enclosed space.

[0008] In the device disclosed in Japanese Published Unexamined PatentApplication No. Sho 64-Sl74, the cooling of the light valve device anddust prevention around the light valve device are not considered, andthe disturbance of normal operation due to the above-describedoverheating and the occurrence of shadows on the screen due to dust havenot been fully considered.

[0009] Further, in the technique disclosed in Japanese PublishedUnexamined Patent Application No. Sho 62-294230, the prevention of dustaround the light valve device is not considered, and the occurrence ofshadows on the screen due to dust has not been fully considered.

[0010] Further, in the technique disclosed in Japanese PublishedUnexamined Patent Application No. Hei 7-152009, since the cooling isperformed via the air present within the enclosed space, efficientcooling cannot be expected. Further, in a case where the amount ofheating increases due to an increase in the light-source lightintensity, the light valve device might not be sufficiently cooled. Inthis case, the display device cannot be normally operated, and thisproblem has not been fully considered.

[0011] Accordingly, the present invention has an object to provide aprojection type display device which efficiently performs dustprevention around the light valve device and cooling of a light valvedevice.

SUMMARY OF THE INVENTION

[0012] To attain the foregoing object, the present invention providesvarious features.

[0013] As a first feature, there is provided a display device whichperforms image display based on light reflected from a reflecting typelight valve means, wherein said reflecting type light valve means isprovided in a partition wall forming an enclosed space including atleast an incidence/emission optical system of said reflecting type lightvalve means, in a state where at least a part opposite to a lightincidence/emission surface of said light valve means is connected tocooling means disposed outside said enclosed space.

[0014] As a second feature, there is provided a display device whichperforms image display based on light reflected from a reflecting typelight valve means, comprising: a partition wall that forms an enclosedspace including at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is set on the sideof said enclosed space, and wherein a part opposite to said lightincidence/emission surface is connected to cooling means.

[0015] As a third feature, a display device is provided which generatesan image display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a transparentmember is provided on a light incidence/emission surface of said lightvalve means, and a part opposite to said light incidence/emissionsurface is connected to cooling means outside said enclosed space.

[0016] As a fourth feature, a display device is provided which generatesan image display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is on the side ofsaid enclosed space, and wherein a radiation member is connected to apart opposite to said light incidence/emission surface such that saidradiation member is cooled by a cooling member.

[0017] As a fifth feature, a display device is provided which generatesan image display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, and cooling means, disposed outsidesaid enclosed space, for cooling at least said partition wall, whereinsaid reflecting type light valve means is provided within said enclosedspace, and wherein a part opposite to a light incidence/emission surfaceof said light valve means is connected to said partition wall, wherebysaid reflecting type light valve means is cooled by said cooling meansvia said partition wall.

[0018] As a sixth feature, a display device is provided which generatesan image display based on light reflected from a reflecting type lightvalve means, wherein said reflecting type light valve means is providedin a partition wall forming an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans.

[0019] As a seventh feature, a display device is provided whichgenerates an image display based on light reflected from a reflectingtype light valve means, comprising: a partition wall that forms anenclosed space including at least an incidence/emission optical systemof said reflecting type light valve means, wherein said reflecting typelight valve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is on the side ofsaid enclosed space, and a part opposite to said lightincidence/emission surface is outside said enclosed space.

[0020] As an eighth feature, a display device is provided whichgenerates an image display based on light reflected from a reflectingtype light valve means, comprising: a partition wall that forms anenclosed space including at least an incidence/emission optical systemof said reflecting type light valve means, wherein said reflecting typelight valve means is provided in said partition wall such that atransparent member is provided on a light incidence/emission surface ofsaid light valve means and a part opposite to said lightincidence/emission surface is outside said enclosed space.

[0021] As a ninth feature, a display device is provided which receiveslight from a light source into a reflecting type light valve means andgenerates an image display based on reflected light, comprising: apartition wall that forms an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans, wherein said reflecting type light valve means is provided insaid partition wall such that a light incidence/emission surface of saidlight valve means is on the side of said enclosed space, and wherein aradiation member is connected to a part opposite to said lightincidence/emission surface.

[0022] As a tenth feature, a display device is provided which generatesan image display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means and that has thermal conductivity,wherein said reflecting type light valve means is provided in saidenclosed space, and wherein a part opposite to a lightincidence/emission surface of said light valve means is connected tosaid partition wall.

[0023] As an eleventh feature, a display optical system unit is providedwhich receives light from a light source into a reflecting type lightvalve means, then passes reflected light through a projection lens, andforms image display projection light, comprising: a partition wall thatforms an enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means, wherein saidreflecting type light valve means is provided in said partition wall ina state where a part opposite to a light incidence/emission surface ofsaid light valve means is connected to cooling means outside saidenclosed space.

[0024] As a twelfth feature, a display optical system unit is providedwhich receives light from a light source into reflecting type lightvalve means, then passes reflected light through a projection lens, andforms image display projection light, comprising: a partition wall thatforms an enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means, wherein saidreflecting type light valve means is provided in said partition wall ina state where a transparent member is provided on a lightincidence/emission surface of said light valve means.

[0025] As a thirteenth feature, a display optical system unit isprovided which receives light from a light source into reflecting typelight valve means, then passes reflection light through a projectionlens, and forms image display projection light, comprising: a partitionwall that forms an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans, wherein said reflecting type light valve means is provided insaid partition wall in a state where a light incidence/emission surfaceof said light valve means is on the side of said enclosed space, and aradiation member is connected to a part opposite to said lightincidence/emission surface such that said radiation member is cooled bycooling means.

[0026] As a fourteenth feature, a display optical system unit isprovided which receives light from a light source into reflecting typelight valve means, then passes reflection light through a projectionlens, and forms image display projection light, comprising: a partitionwall that forms an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans and that has thermal conductivity, wherein said reflecting typelight valve means is provided in said enclosed space, and wherein a partopposite to a light incidence/emission surface of said light valve meansis connected to said partition wall, whereby said reflecting type lightvalve means can be cooled by external cooling means via said partitionwall.

[0027] According to the above constructions, the occurrence of shadowsin a projection image due to dust can be prevented. Further, radiationand cooling on the reflecting type light valve means can be efficientlyperformed.

BRIEF DESCRIPTION OF DRAWINGS

[0028]FIG. 1 is a perspective view showing the external appearance of adisplay device according to a first embodiment of the present invention;

[0029]FIG. 2 is a perspective view showing the internal structure of thedisplay device according to the first embodiment of the presentinvention;

[0030]FIG. 3 is a perspective view showing the internal structure of anoptical chassis of the display device according to the first embodimentof the present invention;

[0031]FIG. 4 is a cross sectional view showing the structure of thedisplay device according to the first embodiment of the presentinvention;

[0032]FIG. 5 is a cross sectional view showing the structure of thedisplay device according to a second embodiment of the presentinvention;

[0033]FIG. 6 is a cross sectional view showing the structure of thedisplay device according to a third embodiment of the present invention;

[0034]FIG. 7 is a cross sectional view showing the structure of thedisplay device according to a fourth embodiment of the presentinvention;

[0035]FIG. 8 is an expanded cross sectional view showing a liquidcrystal panel attachment portion of the display device according to thefourth embodiment of the present invention;

[0036]FIG. 9 is a cross sectional view showing the structure of thedisplay device according to a fifth embodiment of the present invention;

[0037]FIG. 10 is a cross sectional view showing the structure of thedisplay device according to a sixth embodiment of the present invention;

[0038]FIG. 11 is a cross sectional view showing the structure of thedisplay device according to a seventh embodiment of the presentinvention; and

[0039]FIG. 12 is a cross sectional view showing the structure of thedisplay device according to an eighth embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0040] Hereinbelow, the present invention will be described in detailwith reference to the accompanying drawings.

[0041] A first embodiment of the present invention will be describedwith reference to FIGS. 1 to 4.

[0042]FIG. 1 shows the external appearance of a display device. In adisplay device 1 shown in FIG. 1, a part of a projection lens 4 isexposed outside an outer casing of the display device. A video image isprojected on an external screen or the like from the projection lens 4.Further, an outlet port 14 is provided in the front side, and an inletport 11 is provided near the rear side. External air is taken from theinlet port 11 and is used for cooling the inside the device, then theheated air is discharged from the outlet port 14 to the outside of thedevice.

[0043]FIG. 2 shows the display device of FIG. 1 as seen when a sidecover of the device is removed. As shown in FIG. 2, a video displaymechanism is provided in the display device 1. The video displaymechanism comprises an optical chassis 15 sealed by a cover 16 and lightsource members 21 to 23. The details of the respective parts shown inFIG. 2 will be described later with reference to FIG. 4.

[0044]FIG. 3 shows the structure of FIG. 2 as seen when the cover 16 ofthe optical chassis 15 is removed. The inside of the optical chassis 15comprises a space 5 which is sealed from the outside to prevent dustfrom entering by attachment of the cover 16. In the followingdescription of the embodiment, this space 5 will be referred to as an“enclosed space” and the sealed chassis 15 will be referred to as an“enclosure”.

[0045] Hereinbelow, the respective parts will be described in detailwith reference to FIG. 4, which represents a cross section of thedisplay device 1 in this status.

[0046] As shown in FIG. 4, a video display mechanism is provided in thedisplay device 1. The video display mechanism comprises the opticalchassis 15 and a light source portion. Light emitted from the lightsource portion is reflected by a light-polarizing type reflection liquidcrystal panel 3, operating as a reflecting type light valve, and thereflected light is directed toward the outside of the device 1 via theprojection lens 4, where the light is projected on a screen (not shown).The light source portion includes an electric bulb 2, a reflector 21 andcondenser lenses 22 and 23. Light from the electric bulb 2 is collectedby the reflector 21, is formed into an approximately collimated lightbeam via condenser lenses 22 and 23, and passes into the optical chassis15.

[0047] The light from the condenser lens 23 passes through an incidencecover glass 24 made of transparent material into the optical chassis 15.The incidence cover glass 24 is provided as a part of a partition wallto seal the inside of the optical chassis 15. The light which hasentered the optical chassis 15 passes through a cover glass 33 providedin front of the liquid crystal panel 3, and is reflected by the liquidcrystal panel 3, which operates as a reflecting type light valve device.The cover glass 33 is provided as a part of the partition wall to sealthe inside of the optical chassis 15. The liquid crystal panel 3 is intight contact with the cover glass 33, so that no extraneous gas entersbetween the cover glass 33 and the liquid crystal panel 3.

[0048] The light reflected by the liquid crystal panel 3 again passesthrough the cover glass 33, then, passes through the projection lens 4,and is projected toward the outside. The projection lens 4 is alsoprovided as a part of the partition wall of the optical chassis 15 toseal the inside of the optical chassis 15.

[0049] In the entire optical system, among the optical axes, a sectionfrom the incidence cover glass 24 to the cover glass 33 and a sectionfrom the cover glass 33 to the projection lens 4 are disposed inside theenclosed space 5 and are sealed from the outside. On the optical axes,the front and rear of the liquid crystal panel 3 are in enclosed spaces;therefore, dust or the like cannot enter from the outside. Accordingly,when an image displayed on the liquid crystal panel 3 is projected andthe focal point of the projection lens 4 is adjusted to obtain a sharpimage from the liquid crystal panel 3, since the liquid crystal panel 3and its peripheral portion are in an enclosed space, dust or the likecan not collect around the focal point and so no shadow occurs in theprojected video image.

[0050] The liquid crystal panel 3 comprises a two-dimensionally arrangedmatrix of liquid crystal cells corresponding to two-dimensionallyarranged pixels (e.g., 1024 pixels in a horizontal direction and 768pixels in a vertical direction, i.e. , total 786432 pixels) for formingan image. The liquid crystal panel controls whether light is reflectedor absorbed by the liquid crystal panel 3, per pixel, by selectivelycontrolling the ON/OFF state of each liquid crystal cell based on animage signal supplied from an image display circuit (not shown), wherebyan image is displayed. For example, for a liquid crystal panel in whichlight is reflected when the liquid crystal is in the off state, andlight is absorbed when the liquid crystal is in the on state, a pixelcorresponding to a bright part of an image is turned off, while a pixelcorresponding to a dark part is turned on. In this manner, reflectionand absorption is selectively controlled for respective pixels whichform a two dimensional video image, and an image is displayed on thetwo-dimensional surface of the liquid crystal panel 3. Then, the imageformed on the surface of the liquid crystal panel 3 is projected as anenlarged image on the external screen (not shown) by the projection lens4.

[0051] The liquid crystal panel 3 reflects or absorbs incident light inaccordance with the contents of an image to be displayed. The absorbedlight becomes thermal energy and raises the temperature of the liquidcrystal panel. Further, even when light is reflected, all the light isnot reflected, but a part of the light is absorbed into the liquidcrystal panel 3 and becomes thermal energy. When the generated thermalenergy is at a maximum level, the entire content of the image is black,for example, and almost all the incident light is absorbed. That is, tooperate the liquid crystal panel within its operational temperaturerange, radiation corresponding to the energy generated in the panel mustbe provided.

[0052] In the present embodiment, thermal energy generated in the liquidcrystal panel 3 is radiated and cooled by cooling means provided on aradiation surface on the rear side of the liquid crystal panel 3. Thatis, a radiation fin 31 is attached to the rear surface of the liquidcrystal panel 3, and the heat generated in the liquid crystal panel 3 istransmitted to the radiation fin. The radiation fin 31 is cooled by anair flow from a radiation fan 6. The radiation fan 6 is supplied withoutside air sucked into the inlet port 11. Thus, the radiation fin 31 iscooled with air having a temperature which is always close to that ofthe outside air.

[0053] For cooling the entire display device 1, the outside air issucked into the inlet port 11 by a cooling fan 7 and is discharged fromthe outlet port 14. The outside air is always supplied around theradiation fan 6 and the radiation fin 31 to provide cooling for the rearof the panel.

[0054] Further, the air used for cooling around the liquid crystal panelis also used for cooling around the electric bulb 2, i.e., the reflector21 and the condenser lenses 22 and 23, and is discharged by the fan 7from the outlet port 14 to the outside the device 1. By thisarrangement, the heat generated in the device can be effectivelydischarged to the outside the device.

[0055] In this manner, in the first embodiment, parts related to theoptical system of the liquid crystal panel 3 are sealed in an enclosedspace, and heat generated in the enclosed space is sent to the outsidethe enclosed space and radiated away. This attains both advantages ofprevention of dust on the side of the incidence/emission surface of theliquid crystal panel and prevention of a temperature rise.

[0056] Hereinbelow, a second embodiment of the present invention will bedescribed. FIG. 5 shows the structure of the display device 1 accordingto the second embodiment. FIG. 5 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

[0057] The difference between this embodiment and the first embodimentshown in FIG. 4 is that, in the present embodiment, the liquid crystalpanel 3, operating as a reflecting type light valve means, is directlyprovided in the wall of the enclosed space 5, so that the liquid crystalpanel 3 forms part of the partition wall of the optical chassis 15. Theradiation surface on the rear of the liquid crystal panel 3 facesoutwardly from the partition wall of the enclosed space 5, and theradiation fin 31 serving as part of the cooling means is attached there.Further, the image display surface of the liquid crystal panel 3 whereincidence/emission of light occurs is within the enclosed space. Withthis arrangement, in addition to the advantages of the first embodiment,the cover glass which forms a window in the partition wall member isunnecessary, which simplifies the structure of the device.

[0058] Hereinbelow, a third embodiment of the present invention will bedescribed. FIG. 6 shows the structure of the display device 1 accordingto the third embodiment. FIG. 6 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

[0059] The difference between the third embodiment and the firstembodiment shown in FIG. 4 is that, in the present embodiment, theentire liquid crystal panel 3, operating as a reflecting type lightvalve means, is disposed within the enclosed space of the opticalchassis 15, and the radiation fin 31, which forms a part of theradiation means connected to the radiation surface on the rear of theliquid crystal panel 3, serves as part of the partition wall of theoptical chassis 15. In this arrangement, as in the case of the secondembodiment, the structure of the device can be further simplified incomparison with the first embodiment.

[0060] Hereinbelow, a fourth embodiment of the present invention will bedescribed. FIG. 7 shows the construction of the display device 1according to the fourth embodiment. FIG. 7 shows a cross section of thedisplay device 1 as in the case of FIG. 4.

[0061] The difference between the first embodiment shown in FIG. 4 isthat, in the present embodiment, the liquid crystal panel 3, operatingas a reflecting type light valve means, is connected to the partitionwall of the optical chassis 15 forming the enclosed space 5 via aflexible bellows 34. In the present embodiment, as shown in FIG. 8,which represents an enlarged view of the liquid crystal panel 3 and thebellows 34, the bellows 34 and the liquid crystal panel 3 form a part ofthe partition wall of the enclosed space 5.

[0062] In some cases, the attachment position of the liquid crystalpanel 3 must be adjusted to a predetermined reflection angle andposition so as to correctly project a video image. In such case,according to the present embodiment, since the bellows 34 is providedbetween the wall forming the enclosed space of the optical chassis 15and the liquid crystal panel 3, even if the attachment position of theliquid crystal panel 3 is moved, the flexible bellows 34, in a distortedstate, will maintain the integrity of the enclosed space.

[0063] In this manner, the adjustment is simple, and upon adjustment,the entrance of dust into the optical chassis can be prevented.

[0064] Hereinbelow, a fifth embodiment of the present invention will bedescribed. FIG. 9 shows the structure of the display device according tothe fifth embodiment. FIG. 9 shows a cross section of the display device1 as in the case of FIG. 4.

[0065] The fifth embodiment is capable of producing a color video imageprojection by providing three reflecting type light valve means,corresponding to the three primary colors of a video image, andproviding light separation/combining means for use with respect to thethree primary colors in the optical path.

[0066] In this display device, light generated from the electric bulb 2becomes approximately collimated light, via the reflector 21 and thecondenser lenses 22 and 23, and passes into the enclosed space 5 of theoptical chassis 15 via the incidence cover glass 24. In the enclosedspace 5, a dichroic mirror 36 and a dichroic mirror 35 are provided,respectively, for reflecting a blue color component of light having,e.g., a half-value breadth range of 400-500 nm, a red color component oflight having, e.g., half-value breadth range of 600-700 nm, and forpassing the other light component. The blue color component of light isreflected by the dichroic mirror 36, and is directed toward a liquidcrystal panel 3B. The remaining green and red color components passthrough the dichroic mirror 35 and continue toward the next dichroicmirror 35. The red color component of light is reflected by the dichroicmirror 35 and is directed toward a liquid crystal panel 3R. Theremaining green color component of light having, e.g., a wavelengthrange of 500-600 nm passes through the dichroic mirror 35 and continuestoward the liquid crystal panel 3.

[0067] Lights reflected by the liquid crystal panels operating asreflecting type light valve means, so that the green color component oflight is reflected from the liquid crystal panel 3 and is directedtoward the dichroic mirror 35. The red color component of light isreflected from the liquid crystal panel 3R and is directed toward thedichroic mirror 35. The red color component of light is again reflectedby the dichroic mirror 35, and is directed toward the projection lens 4.The red color component of light is combined with the green component oflight which again passes through the dichroic mirror 35. Next, the bluecolor component of light is again reflected by the dichroic mirror 36and is directed toward the projection lens 4. At this time, the bluecolor component of light is combined with the green color component andred color component of light. In this manner, the light finally entersthe projection lens 4, and the light to be projected includes acombination of the blue, green and red primary color components.

[0068] At this time, if the reflection angles, distances and parallelismand the like at the three liquid crystal panels are shifted from eachother, the combined image will experience a shift in the colors, and,finally, a video image having an undesirable color shift will beprojected.

[0069] Accordingly, the positions of the liquid crystal panels areadjusted to correct any color shift. As in the case of the fourthembodiment, a flexible bellows is attached between the respective liquidcrystal panels and the wall of the optical unit 15, so that, even if theposition of the liquid crystal panel is adjusted, the bellows maintainsthe integrity of the enclosed space.

[0070] The liquid crystal panels for the three primary colors, whichoperate as reflecting type light valve means, display images of therespective color components. The three liquid crystal panels arerespectively provided with cooling means similar to the previousembodiments. Radiation fin 31B is attached to the liquid crystal panel3B for the blue color component, and a flow of air from a radiation fan6B is directed at the fin. Radiation fin 31R is attached to the liquidcrystal panel 3R for the red color component, and a flow of air from aradiation fan 6R is directed at the fin. Further, radiation fin 31 isattached to the liquid crystal panel 3 for the green color component,and a flow of air from the radiation fan 6 is directed at this fin. Inthis manner, respective cooling means are provided for the three colorcomponents.

[0071] Air flow from the inlet port 11 is supplied to the cooling meansfor the three color components, and the air which is heated afterthermal exchange is used for finally cooling the light source portionand than is discharged by the discharge fan 7 from the outlet port 14 tothe outside the device 1.

[0072] In this manner, even in a color projection device using threepanels for the three color components, the liquid crystal panels can bedisposed in communication with the optical system within the enclosedspace, as well as with the cooling means provided outside of theenclosed space.

[0073] Hereinbelow, a sixth embodiment of the present invention will bedescribed. FIG. 10 shows the structure of the display device accordingto the sixth embodiment. FIG. 10 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

[0074] In the present embodiment, the enclosed space is disposed onlyaround the liquid crystal panel which operates as a reflecting typelight valve means. This reduces the size of the enclosed space, and uponadjustment of position at which the liquid crystal panel 3 is attachedto the wall of the enclosed space, the entire enclosed space can bemoved. Thus, adjustment can be easily made.

[0075] Hereinbelow, a seventh embodiment of the present invention willbe described. FIG. 11 shows a cross section of a video image displayapparatus according to the seventh embodiment. In this video imagedisplay apparatus, a display device having a construction similar to oneof the above-described first to sixth embodiments is employed to projecta video image on a screen 19 which forms part of the apparatus, ratherthan on an external screen or the like, as previously described.

[0076] In FIG. 11, the optical chassis 15 is attached inside of arear-surface projection type display device 1′. The inside of theoptical chassis 15 is similar to that shown in FIGS. 2 to 9. A videoimage projected from the projection lens 4 of the optical chassis 15passes through a mirror 17 and a mirror 18, and is projected onto ascreen 19 so as to be displayed. Note that in FIG. 11, the light sourceis omitted.

[0077] In this manner, a display device is incorporated in arear-surface projection type display apparatus and, has similaradvantages to those described with reference to the first to sixthembodiments.

[0078] Hereinbelow, an eighth embodiment of the present invention willbe described. FIG. 12 shows the structure of the display deviceaccording to the eighth embodiment. FIG. 12 shows a cross section of thedisplay device as in the case of FIG. 4.

[0079] The difference between this embodiment and the first embodimentshown in FIG. 4 is that, in the eighth embodiment, the liquid crystalpanel 3, which operates as a reflecting type light valve means, isprovided entirely within the enclosed space 5, and the radiation surfaceside of the panel on the rear surface thereof is directly in contactwith the wall surface of the optical chassis 15. In this arrangement,the wall surface of the optical chassis 15 can be used as a coolingmeans. The liquid crystal panel 3 can be cooled by cooling the outsideof the optical chassis 15 by using the radiation fan 6 or the like. Notethat in this case, the wall of the optical chassis 15 is formed of amaterial having a good thermal conductivity, such as a metal.

[0080] Various embodiments of the video image display device accordingto the present invention have been described above. Note that in theabove description, the light-polarizing light-reflecting liquid-crystalpanel is used as a reflecting type light valve means, however, lightvalve devices of other types, e.g., a reflecting type light valve meansof the scattering light-reflecting liquid-crystal panel type, amicro-mirror (micro-mirror drive) type panel, a laser-liquid-crystalwriting reflecting type panel and the like, can be employed, and similaradvantages can be obtained.

[0081] Further, in the above description, the optical system uses adioptric lens, however, optical devices other than a dioptric lens, suchas a reflection mirror lens or a combination of a dioptric lens and areflection mirror lens may be used.

[0082] Further, if only the part of video image display mechanism (thepart in the external casing of the video display device) or the opticalchassis is directly provided in a building or the like, the externalpart may be integrated with the building, and similar advantages can beobtained.

[0083] Further, in the fourth embodiment described above, a memberhaving a bellows structure is used as a flexible member connecting theliquid crystal panel to the optical chassis, however, any other flexiblemembers which do not allow dust to pass, such as sponge foam, may beemployed. In this case, similar advantages can be obtained. That is, inthe above embodiments, the enclosed space 5 may be employed as long asit is sealed against dust, and this does not pose any limitation on thescope of the present invention.

[0084] As described above, in the various embodiments, the side of theincidence/emission surface of a reflecting type light valve device isprovided in a space sealed (protected) against dust, and a radiationsurface on the rear surface side of the light value device is connectedto cooling means outside the enclosed space. This efficiently dissipatesheat generated in the reflecting type light valve means and prevents theentrance of dust from the outside into the enclosed space. Further, theattachment position of the light valve device can be adjusted withoutbreaking the seal of the enclosed space by connecting the light valvedevice to the optical chassis with a flexible member.

[0085] As described above, according to the present invention, aprojection type display device which prevents dust from collectingaround a light valve device and efficiently cools the light valve devicecan be provided.

[0086] The display device according to the present invention isavailable as a liquid crystal projector device, a liquid crystaltelevision set, a projection type display device and the like, and thepresent invention is especially applicable to efficient execution ofdust prevention around a light valve device and cooling with respect tothe light valve device.

1. A display apparatus comprising: a reflecting type light valve whichhas a light incidence/reflection surface; a drive circuit which drivessaid reflecting type light valve by supplying an image signal; a coolingsystem which cools at least said reflecting type light valve withcooling fluid; and a partition wall which partitions a space in saiddisplay apparatus into a cooling fluid side and a lightincidence/reflection side; wherein said reflecting type light valveforms a part of said partition wall, and said light incidence/reflectionsurface faces said light incidence/reflection side; and wherein a partopposite to said light incidence/reflection surface of said reflectingtype light valve is cooled by said cooling system.
 2. A displayapparatus according to claim 1, further comprising a flexible memberwhich is attached to said light incidence/reflection surface of saidreflecting type light valve for adjusting said reflecting type lightvalve to a predetermined reflection angle and position so as tocorrectly project an image.
 3. A display apparatus comprising: areflecting type light valve which has a light incidence/reflectionsurface; a drive circuit which drives said reflecting type light valveby supplying an image signal; a cooling system which cools at least saidreflecting type light valve with cooling fluid; a light through memberwhich is provided on a side of said light incidence/reflection surface;and a partition wall which partitions a space in said display apparatusinto a cooling fluid side and a light incidence/reflection side; whereinsaid light through member forms a part of said partition wall, andwherein a part opposite to said light incidence/reflection surface ofsaid reflecting type light valve is cooled by said cooling system.
 4. Adisplay apparatus according to claim 3, further comprising a flexiblemember which is attached to said light incidence/reflection surface ofsaid reflecting type light valve for adjusting said reflecting typelight valve to a predetermined reflection angle and position so as tocorrectly project an image.